Initialization of a sensor for minitoring the structural integrity of a building

ABSTRACT

Initialization of a sensor for monitoring the structural integrity of a building involves the sensor, a gateway and an installer device. An automated initialization brings the sensor online and enables the sensor for remote monitoring without requiring on-site manual configuration. Through the automated initialization, the sensor joins a logical communication group and a GPS location associated with the sensor becomes remotely accessible by a human network administrator.

CROSS REFERENCE TO RELATED APPLICATIONS

This application has subject matter related to the following U.S.nonprovisional applications, all having filing dates concurrentherewith, and all of which are incorporated herein by reference: Ser.No. __/______ entitled “DIGITAL COMMUNICATION SYSTEM FOR MONITORING THESTRUCTURAL INTEGRITY OF A BUILDING AND SENSOR THEREFOR;” Ser. No.__/______ entitled “REMOTE CONFIGURATION OF A SENSOR FOR MONITORING THESTRUCTURAL INTEGRITY OF A BUILDING;” Ser. No. __/______ entitled “LINKESTABLISHMENT IN A SYSTEM FOR MONITORING THE STRUCTURAL INTEGRITY OF ABUILDING;” and Ser. No. __/______ entitled “POWER CONSERVING MODE FOR ASENSOR FOR MONITORING THE STRUCTURAL INTEGRITY OF A BUILDING.”

BACKGROUND OF THE INVENTION

In recent years, moisture intrusion has become a more significantconcern in facilities management. Moisture intrusion into building wallscan result from the failure of weather resistive barriers that areimproperly designed or installed, or that have been subjected toprolonged exposure to the elements. If left unchecked, moistureintrusion can lead to an array of serious problems, including mold, rotand structural instability. Business liability arising from moisturerelated problems has skyrocketed, to the point where many insurers haveeliminated or restricted coverage for water damage in their policies.

Many moisture intrusion problems that eventually require expensivesolutions are detectable through monitoring before they cause acutedamage. One known monitoring solution is to install electrical moisturesensors in building walls and periodically test for moisture content. InU.S. Pat. No. 6,377,181, for example, it is described to embed multiplemoisture sensors in walls and electrically connect them to a centralcontrol unit. The central control unit periodically sends an excitationvoltage to each sensor and measures a voltage drop across the sensor,from which the central control unit directly calculates the wall'smoisture content using a resistance curve.

This known solution is severely limited in terms of its informationyield and overall sophistication. First, the sensors in the knownsolution are monolithic devices that are only capable of conveying onetype of information, namely, a voltage drop indicative of moisturecontent. These prior art sensors are incapable of conveying informationon other parameters indicative of structural integrity, such astemperature and humidity, or operational parameters, such as thesensor's location, operational state and the time of day.

Second, the sensors in this known solution are passive devices that areincapable of initiating information transfer. These sensors must wait tobe driven by a periodic excitation voltage to send information to thecentral control unit. They are incapable, for example, of initiatingtransmission of an alarm notification to the central control unit upondetecting that a threshold for a parameter relevant to structuralintegrity has been surpassed.

Third, the sensors in this known solution are immutable devices that arenot programmatically initializable, configurable or upgradeable. Thesesensors are not, for example, programmable to bring them online orspecify the parameters relating to structural integrity to be monitored,or the operational parameters to be used in monitoring, such asmeasuring frequency, reporting frequency and alarm thresholds.

There is accordingly a need for a solution for monitoring structuralintegrity of a building that yields more information and provides a moreadvanced feature set.

SUMMARY OF THE INVENTION

In one aspect of the invention, a system and method for monitoring thestructural integrity of a building is provided wherein the system andmethod comprise a sensor coupled to the building that communicatesstructural integrity information to a gateway via a digitalcommunication link. The digital communication link is preferably abidirectional wireless link that supports packetized data transferbetween the sensor and the gateway. By supporting communication betweenthe sensor and the gateway via a bidirectional digital communicationlink, the sensor is advantageously able to serve as a multidimensionaldevice for reporting numerous types of structural integrity andoperational information, an active device for initiating transfer ofstructural integrity and operational information, and a mutable devicethat is programmatically initializable, configurable and upgradeable tobring the sensor online and specify the parameters relating tostructural integrity to be monitored and the operational parameters tobe used in monitoring. Information and parameters relating to structuralintegrity (hereinafter “structural integrity information” and“structural integrity parameters,” respectively) include, by way ofexample, information and parameters, respectively, relating to moisturecontent, humidity or temperature within a building envelope.

In another aspect of the invention, such a sensor is made operational bycompleting a fully automated initialization protocol involving thesensor, such a gateway and an installer device. Upon power up or resetof the sensor, the sensor establishes a first digital communication linkwith the installer device. Over the first digital communication link,the sensor learns first configuration information from the installerdevice. The sensor then establishes a second digital communication linkwith the gateway. Over the second digital communication link, thegateway learns the first configuration information from the sensor. Thesensor then establishes a third digital communication link with theinstaller device. Over the third digital communication link, theinstaller device learns that the portion of the initialization protocoloccurring between the sensor and the gateway was successful and outputsa success indication, such as an audible sound, to indicate successfulinitialization to a human installation technician. The firstconfiguration information preferably includes a network identifieridentifying the sensor with a logical group of devices, and globalpositioning system (GPS) coordinates identifying the approximategeographic location of the sensor. The gateway preferably passes via theInternet the first configuration information to a Web server accessibleby a human network administrator for remotely monitoring the system.Through the expedient of this initialization protocol, the sensor isbrought online and enabled for remote monitoring without requiringon-site manual configuration of the sensor.

In another aspect of the invention, such a sensor is configurable toreport periodic and, optionally, event-driven structural integrity andoperational information to such a gateway. Operational parameters storedon the sensor specify what structural integrity parameters to measure,how frequently to measure them, and how frequently to establish adigital communication link with the gateway allowing periodicinterrogation of structural integrity information recorded by thesensor. Operational parameters stored on the sensor may also optionallyspecify alarm thresholds respecting one or more structural integrityparameters that are continuously monitored and which, if surpassed,cause the sensor to establish a digital communication link with thegateway enabling interstitial interrogation of structural integrityinformation recorded by the sensor.

In another aspect of the invention, such a gateway transmitsconfiguration changes to such a sensor over such digital communicationlinks established for interrogation of structural integrity information.Configuration changes are prompted by a human network administrator whomay be remote from the gateway and sensors. Using a standard Webbrowser, the human network administrator preferably visits a systemmanagement Web site hosted on such a Web server and specifies theconfiguration changes to be made, the sensor or sensor group to whichthe changes are to apply and, in some embodiments, the time the changesare to become effective. The Web server thereafter instructs the gatewayto implement changes to the sensors in the specified manner.

In another aspect of the invention, in intervals between monitoring andreporting of structural integrity information, such a sensor enters apower conserving sleep mode in which the supply of power is inhibited tononessential functions, including sensing functions and radio functions.A real time clock on the sensor preferably prompts periodic wake up ofthe sensor from sleep mode, at which time the supply of power to thesensing functions and radio functions is resumed, if indicated, toperform monitoring and reporting of structural integrity information.

In another aspect of the invention, such digital communication links areestablished between such a sensor and installer device, and between sucha sensor and gateway, using a frequency hopping spread spectrum (FHSS)hunt algorithm in which the sensor's role is limited, thereby minimizingthe sensor's power consumption and extending its battery life.

These and other aspects of the invention will be better understood byreference to the following detailed description taken in conjunctionwith the drawings that are briefly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system for monitoring the structuralintegrity of a building in a preferred embodiment of the invention.

FIG. 2 is a block diagram of a sensor in the system of FIG. 1.

FIG. 3 is a block diagram of gateway in the system of FIG. 1.

FIG. 4 is a flow, diagram describing, from the perspective of theinstaller and gateway of FIG. 1, a FHSS hunt protocol for establishing adigital communication link in the system of FIG. 1.

FIG. 5 is a flow diagram describing, from the perspective of a sensor ofFIG. 1, a FHSS hunt protocol for establishing a digital communicationlink in the system of FIG. 1.

FIG. 6 is a flow diagram describing sensor initialization in the systemof FIG. 1.

FIG. 7 is a flow diagram describing sensor reporting in the system ofFIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

I. System

Referring to FIG. 1, a system 10 for monitoring the structural integrityof a building is shown. System 10 includes an Internet gateway 20interconnecting a multiple of sensors 30, 40, 50 embedded or mountedwithin a building envelope with a Web server 60 from which system 10 canbe monitored by a human network administrator from a monitoring station70 remote from sensors 30, 40, 50. System 10 also includes an installer80, which is a handheld mobile device used by a human installationtechnician to initialize sensors 30, 40, 50. In the illustrated example,sensors 30, 50 are embedded in the walls of a building 90, which may bea commercial or residential structure, whereas sensor 40 is embedded inthe floor. It will be appreciated, however, that sensors operativewithin the invention may be embedded in or mounted to any part of abuilding, including but not limited to walls, floors and roofs. Sensors30, 40, 50 measure and record structural integrity information, such asmoisture content, humidity and temperature information, proximate thelocation where they are embedded or mounted. Internet gateway 20 andsensors 30, 40, 50 communicate over digital communication links 90established using a wireless local area network (LAN) protocol. Internetgateway 20 and Web server 60 communicate over a wired digitalcommunication link using one or more Internet protocols, such as TCP/IP,Asynchronous Transfer Mode (ATM) or MPLS (Multiprotocol LabelSwitching). While one gateway 20 and three sensors 30, 40, 50 are shownin the example shown in FIG. 1, a system operative within the inventioncan include one or more sensors and one or more gateways.

II. Sensor

Turning to FIG. 2, a functional diagram of a representative one ofsensors 30, 40, 50 is shown. Representative sensor 200 includes aprocessing module 210, a sensing module 220, a radio module 230 and abattery 240. Each module is preferably implemented in a distinctcomputer chip on a printed circuit board shared by all of the computerchips. Processing module 210 includes a microprocessor 212 andassociated memory 214. Memory 214 stores a firmware image serving as theoperating system for sensor 200, as well as operational parametersconfigured during manufacturing, initialization and updating of sensor200 and structural integrity information collected by sensing module 220during operation. Battery 240 is preferably an M sized lithium batterythat powers processing module 210, sensing module 220 and radio module230. Sensor 200 may take any of numerous physical shapes, such ascubical, spherical, cylindrical, conical or pyramidal.

A. Sensor Processing Module

Processing module 210 communicates with sensing module 220 and radiomodule 230 via sets of data pins 250, 252 and regulates the supply ofpower from battery 240 to sensing module 220 and radio module 230 viaindividual power pins 260, 262. With regard to power supply regulation,it is desirable to have a sensor that draws little power so that batterylife is minimally impacted by the current that the sensor draws and thedominant factor in battery life is battery aging. This allows sensors tobe embedded in areas that have limited or no access for maintenanceafter the sensor is initially installed, such as wall stud cavities,built-up roofs, and poured concrete slabs. Accordingly, between checks,monitoring and reporting, sensor 200 enters a low power sleep mode.

While in sleep mode, processing module 210 inhibits the supply of powerto radio module 230 via power pin 262 and inhibits power to sensingmodule 220 via power pin 260. Power supply may also be inhibited tofunctions on processing module 210 except for a real time clock. Thereal time clock on processing module 210 initiates wake up of modules220, 230 from sleep state to resume periodic monitoring and reporting,as indicated, and to interstitially report any alarm conditions. Moreparticularly, if upon wake up the operative monitoring frequencyindicates that it is time to monitor, power is resumed to sensing module220 via power pin 260 to enable monitoring to be performed. If upon wakeup the operative link establishment frequency indicates that it is timeto report, or an alarm threshold has been surpassed, power is resumed toradio module 230 via power pin 262 to enable reporting to be performed.In some embodiments, the configured monitoring frequency and linkestablishment frequency are the same, such that inhibition andresumption of power to sensing module 220 and radio module 230 issynchronized in the absence of alarm conditions. Once the indicatedmonitoring and reporting are completed, the real time clock is reset andsleep mode is re-entered.

In alternative embodiments, monitoring of structural integrityparameters for which alarm thresholds are active is continuous, andconsequently the supply of power to sensing module 220 is continuous ifany alarm threshold is active. In still other embodiments, a sensingmodule is divided into multiple sub-modules, each having a distinctpower pin, wherein in sleep mode power continues to be supplied tosub-modules that monitor structural integrity parameters associated withan active alarm threshold, but is inhibited to sub-modules that monitorstructural integrity parameters that are not associated with an activealarm threshold. Moreover, in such embodiments, surpassing an alarmthreshold triggers early wake up from sleep mode for reporting alarmconditions.

Numerous operational parameters are stored in memory 214. Suchoperational parameters include a sensor identifier (Sensor ID). TheSensor ID is a globally unique 32-bit address that is programmed into aflash memory portion of memory 214 during manufacturing of sensor 200.The Sensor ID is preferably in the format of ‘YDDDNNNNN’ wherein YY is adecimal two-digit year from zero to 99, DDD is a decimal three-digit dayof year ranging from zero to 364, NNNNN is a five-digit decimal serialnumber. The decimal number created by the above encoding is converted tohex and permanently stored in the flash memory portion.

Operational parameters also include an installer identifier (InstallerID). The Installer ID is a 32-bit address that is stored in the flashmemory portion of memory 214 by installer 80 during initialization ofsensor 200. Once learned from installer 80, the Installer ID is used bysensor 200 to identify a received packet as having originated frominstaller 80.

Operational parameters also include network identifiers (Network IDs).Network IDs are 32-bit addresses that are stored on memory 214. Aninstaller Network ID is stored on sensor 200 during manufacturing toenable sensor 200 to initiate communication with an installer, such asinstaller 80. The installer Network ID is reserved for this purpose.Additionally, an operational Network ID is stored on sensor 200 byinstaller 80 during initialization of sensor 200. The operationalNetwork ID is shared by a logical group of structural integritymonitoring and reporting devices operative within system 10 thatincludes sensor 200, zero or more other sensors, and one or moregateways. The operational Network ID enables sensor 200 to initiatecommunication with an in-range gateway that is within the logical devicegroup of sensor 200 (and therefore with which sensor 200 is allowed tocommunicate), as distinct from an in-range gateway that is in adifferent logical device group (and therefore with which sensor 200 isnot allowed to communicate). Network IDs permit multiple logicalcommunication groups to operate independently within wireless range ofone another. Network IDs also allow administrative policies to beapplied to a group of sensors by reference to a single identifier.Processing module 210 posses appropriate Network IDs to radio module 230for local storage and prepending to outbound packets.

Operational parameters also include a gateway identifier (Gateway ID).The Gateway ID is a 32-bit address stored in memory 214 by a gatewayduring initialization of sensor 200. Once learned from a gateway, theGateway ID is used by sensor 200 to identify a received packet as havingoriginated from a particular in-range gateway that is within the logicaldevice group of sensor 200. In this regard, in a given building multiplegateways having the same Network ID as sensor 200 may be active withinthe range of sensor 200. Gateway ID allows sensor 200 to distinguishbetween such gateways during operation in order to maintain sessionpersistence.

For the remainder of this detailed description, it is assumed thatsensors 30, 40, 50 (including representative sensor 200), and gateway 20share a Network ID and, as a result, form a logical group of deviceswithin system 10.

Operational parameters also include GPS coordinates. GPS coordinates arestored on memory 214 by installer 80 during initialization of sensor200. Gateway 20 then reads the GPS coordinates and transfers them to Webserver 60 where the position information is maintained in databaserecords associated with sensor 200. Thus, when gateway 20 notifies Webserver 60 of a problem reported by sensor 200, the human networkadministrator can pinpoint the geographic coordinates of sensor 200 andlocate the problem. Sensor 200 is preferably powered up or reset nearthe location it is to be installed in order to ensure a high level ofaccuracy of the GPS coordinates stored to memory 214.

Operational parameters also include a monitoring frequency, whichindicates how frequently sensor 200 measures structural integrityparameters and records structural integrity information to memory 214. Adefault monitoring frequency may be stored to memory 214 duringmanufacturing, and later updated by gateway 20.

Operational parameters also include a link establishment frequency,which indicates how frequently sensor 200, in the absence of an alarmcondition, establishes a digital communication link with gateway 20 forinterrogation of structural integrity information recorded by sensor200. A default link establishment frequency may be stored on memory 214during manufacturing, and later updated by gateway 20.

Operational parameters may also include a monitored parameter list. Amonitored parameter list may be in the form of a bit mask that specifieswhich of the several structural integrity parameters sensor 200 iscapable of monitoring are presently enabled for monitoring. For example,the monitored parameter list may consist in a three-bit mask wherein theindividual bits indicate whether monitoring of moisture content,humidity and temperature, respectively, are presently enabled. A defaultmonitored parameter list may be stored on memory 214 duringmanufacturing, and later updated by gateway 20.

Operational parameters may also include alarm thresholds. Alarmthresholds specify limits for particular monitored structural integrityparameters that, if exceeded, trigger establishment of a digitalcommunication link with gateway 20 for interstitial interrogation ofstructural integrity information recorded by sensor 200. Default alarmthresholds may be stored on memory 214 during manufacturing, and laterupdated by gateway 20.

During initialization, reporting and updating operations conducted overestablished digital communication links, gateway 20 and/or installer 80remotely control access to memory 214 by transmitting packetized directmemory access (DMA) commands to sensor 200. Segments in memory 214 aremapped to particular functions so that gateway 20 and installer 80 canread or write information by issuing and transmitting to sensor 200 aDMA command that specifies read or write, the memory segment, and theinformation to be written (in the case of a write command). In responseto DMA commands, microprocessor 212 either writes the information to thespecified memory segment or reads information from the specified segmentand transmits any read information to the issuing one of gateway 20 orinstaller 80. To support writing to the flash memory portion of memory214, the write command has an “erase before write” option that instructsto erase the flash segment prior to writing the information.

The initial firmware image that serves as the operating system forsensor 200 is programmed into a flash memory portion of memory 214during manufacturing. Replacement firmware images, such as maintenancereleases and upgrades, are written in the flash memory portion of memory214 by gateway 20 using packetized DMA commands. The flash memoryportion of memory 214 is partitioned into two sections. When gateway 20issues a DMA command to write a replacement firmware image, thereplacement firmware image is written into the currently unused sectionof the flash memory, and a program counter on microprocessor 212 iswritten to force execution of the replacement firmware image. Thereplacement image then self-checks to make sure it is not corrupted bydoing a cyclic redundancy check (CRC) over the full image. If the CRCfails, the replacement image forces a firmware reboot to the previousimage. If the CRC passes, the replacement image copies its interruptvectors to memory 214 so that the replacement image will thereafterexecute upon firmware reboot, and forces a firmware reboot to thereplacement image. Gateway 20 learns of CRC failures through currentfirmware version information in packets transmitted by sensor 200 andre-attempts firmware replacement using packetized DMA commands uponlearning of such failures.

B. Sensing Module

Sensing module 220 performs sensing functions for sensor 200. Sensingmodule 220 includes probes for measuring structural integrity parametersas instructed by processing module 210 and supplying structuralintegrity information resulting from such measurements to processingmodule 210. Probes include a moisture content probe 222, a humidityprobe 224 and a temperature probe 226. Moisture content probe 222preferably includes a circuit for making and performinganalog-to-digital conversion of dual voltage measurements indicative ofthe moisture content of the wall, roof or floor proximate sensor 200.Processor module 210 stores the digitized moisture content informationthat is output by moisture content probe 222 in memory 214. Sensor 200transmits the moisture content information to gateway 20 duringinterrogation by gateway 20, and gateway 20 relays the information toWeb server 60. In some embodiments, moisture content informationincludes dual voltage measurements made by probe 222 and Web server 60calculates the moisture content of the wall, roof or floor proximate tosensor 200 by reference to the dual voltage measurements. In thoseembodiments, Web server 60 calculates an RC time constant from themeasurements and calculates the moisture content from a knownrelationship with the RC time constant. In other embodiments, a moisturecontent probe may be implemented as a “Wheatstone bridge” circuit whosevoltage varies with the resistance of the wall, roof or floor undertest.

Humidity probe 224 preferably includes a circuit for making andperforming analog-to-digital conversion of relative humiditymeasurements. In some embodiments, probe 224 utilizes a capacitivepolymer sensing element in making such measurements. Temperature probe226 preferably includes a circuit for making and performinganalog-to-digital conversion of temperature measurements. In someembodiments, temperature probe 226 utilizes a bandgap temperature sensorin making such measurements. An integrated humidity/temperature sensor,such as the SHT11 digital humidity and temperature sensor marketed bySensirion AG, may be employed as probes 224, 226. Relative humidity andtemperature information returned to processing module 210 from probes224, 226 is stored in memory 214 until interrogation by gateway 20.

C. Sensor Radio Module

Radio module 230 provides wireless transceiver functions for aconnection oriented wireless LAN communication protocol that enablessensor 200 to communicate with installer 80 and gateway 20. Features ofthe wireless LAN communication protocol include wireless linkestablishment and tear-down and packet formatting. It will beappreciated that these protocol features may be performed by processingmodule 210, with radio module 230 supporting processing module 210 withnecessary transceiver functions.

In wireless link establishment, sensor 200 establishes wireless linkswith installer 80 and gateway 20 by assuming the link slave role in alow power FHSS hunt protocol. Sensor 200 assumes the link slave role onpower up and reset to establish a digital communication link first withinstaller 80 and then gateway 20 for initialization. Sensor 200 alsoassumes the link slave role when reporting is indicated by the linkestablishment frequency or an alarm condition to establish a digitalcommunication link with gateway 20 for interrogation of structuralintegrity information. The FHSS hunt protocol is preferably implementedon processing module 210 under firmwore control.

In packet formatting, sensor 200 packetizes information for transmissioninto fixed length packets, and prepends to each fixed length packet aheader having a source address field, a destination address field and aNetwork ID field. Each packet is preferably 32 bytes in length. TheSensor ID of sensor 200 is inserted in the source address field. Theinstaller Network ID is inserted into the Network ID field whencommunicating with installer 80 and the Installer ID of installer 80,once known, is inserted into the destination address field whencommunicating with installer 80. The operational Network ID of gateway20 is inserted into the Network ID field and the Gateway ID of gateway20, once known, is inserted into the destination address field whencommunicating with gateway 20. Packet formatting is preferablyimplemented on processing module 210 under firmware control, except thatradio module 230 maintains and prepends appropriate Network IDs onpackets.

III. Gateway

FIG. 3 shows gateway 20 in more detail. Gateway 20 includes a processingmodule 310, a radio module 320 for communicating with sensors 30, 40, 50and a wireline module 330 for communicating with Web server 60. Gateway20 is powered either through an external AC power cord or inline powersupplied via wireline module 330. Processing module 310 includes amicroprocessor 312 and memory 314. Memory 314 stores a firmware imageserving as the operating system for gateway 20, operational parametersconfigured during manufacturing, initialization and configuration ofgateway 20, configuration information received from Web server 60awaiting local application or downloading to sensors 30, 40, 50 andstructural integrity information collected from sensors 30, 40, 50awaiting uploading to Web server 60. Processing module 310 communicateswith radio module 320 and wireline module 330 via sets of data pins 340,342.

Operational parameters stored on memory 314 include the Gateway IDassigned to gateway 20, the operational Network ID of the logical groupof devices to which gateway 20 belongs, and an address of Web server 60which may be, for example, an IP address. In other embodiments, theaddress of Web server 60 may be stored on wireline module 330. Gateway20 preferably does not maintain a list of sensors active within itslogical communication group. It can be safely assumed that if a sensoris using a Network ID that matches the gateway's Network ID then thatsensor is a member of the gateway's logical communication group.

Radio module 320 provides wireless transceiver functions for aconnection oriented wireless LAN communication protocol that enablesgateway 20 to communicate with sensors 30, 40, 50. Features of thewireless LAN communication protocol include wireless link establishmentand tear down and packet formatting. It will be appreciated that theseprotocol features may be performed by processing module 310, with radiomodule 320 supporting processing module 310 with necessary transceiverfunctions.

Gateway 20 establishes wireless links with sensors 30, 40, 50 byassuming the link master role in the FHSS hunt protocol. Gateway 20assumes the link master role on power up to announce its readiness toestablish digital communication links with sensors 30, 40, 50. The FHSShunt protocol is preferably implemented on processing module 310 underfirmware control.

Wireline module 330 provides an Ethernet interface for maintaining an“always on” broadband Internet connection to Web server 60, as well as aPSTN interface with a dial up modem for establishing intermittent dialup connections to Web server 60. In some embodiments, wireline module330 includes an embedded Web server supporting Layer 2 and Layer 3functions, such as TCP/IP and DHCP, and storing the IP address of Webserver 60.

IV. Installer

Installer 80 is a handheld mobile device having a processing module, aradio module for communicating with sensors 30, 40, 50, a wirelinemodule for receiving configuration information from a PC over a serialinterface such as an RS-232 interface, and a speaker for making anaudible sound to notify a human installation technician of successfulinitialization of sensors 30, 40, 50. Installer 80 is preferably poweredby AA sized batteries. The processing module on installer 80 has aprocessor and a memory storing a firmware image serving as the operatingsystem for installer 80 and operational parameters configured duringmanufacturing and configuration of installer 80 and awaiting localapplication or downloading to sensors 30, 40, 50. Operational parametersstored on installer 80 include the Installer ID assigned to installer80, the installer Network ID, and the operational Network ID of thelogical group of devices to which the sensors that installer 80 isresponsible for initializing belong.

The radio module on installer 80 provides wireless transceiver functionsfor a connection oriented wireless LAN communication protocol thatenables installer 80 to communicate with sensors 30, 40, 50. Features ofthe wireless LAN communication protocol include wireless linkestablishment and tear down and packet formatting. These protocolfeatures may be performed by the processing module with the radio modulesupporting the processing module with necessary transceiver functions.

Installer 80 establishes wireless links with sensors 30, 40, 50 byassuming the link master role in the FHSS hunt protocol. Installer 80assumes the link master role on power up to announce its readiness toestablish digital communication links with sensors 30, 40, 50. The FHSShunt protocol is preferably implemented on the processing module underfirmware control.

After configuration of installer 80 by a PC over the serial interface ofthe wireline module, a GPS receiver (not shown) can be attached to theserial interface on installer 80 to receive GPS coordinates from anexternal GPS. This enables installer 80 to provide an approximate GPSlocation to sensors 30, 40, 50 during initialization of sensors 30, 40,50.

The speaker is operatively coupled to the processing module of installer80 and is selectively driven by the processing module to sound a seriesof rapid beeps at the same pitch to indicate successful initializationof a sensor.

V. FHSS Hunt Protocol

FIG. 4 is a flow diagram describing the FHSS hunt protocol from theperspective of the link master, for example, gateway 20 or installer 80.In a preferred embodiment, the FHSS hunt protocol uses 127 uniquechannels in the 902 to 928 MHz frequency band to allow many devices tocommunicate at the same time without significant signal interference.The channels are chosen pseudo-randomly. Since under the FHSS protocolthe link master listens and transmits continuously, whereas the linkslave only listens and transmits selectively, gateway 20 and installer80 are configured as FHSS link masters, whereas sensors 30, 40, 50 areconfigured FHSS link slaves, to conserve the battery life of sensors 30,40, 50.

The link master, for example, gateway 20 or installer 80, listens to achannel to verify that it is currently not in use (410). The link masterthen transmits a HELLO beacon for approximately 50 ms (420), then sendsa HELLO_END packet to signal the end of the beacon transmission (425),and then listens for approximately four ms for an ACK packet type fromany sensor that heard the beacon (430). The HELLO_END packet containsinformation sufficient to identify the link master and the channelnumber the link master is transmitting on. The channel number istransmitted because it is possible for a sensor to receive a packet on achannel different from that on which it was sent. If no ACK response isreceived (440), the link master hops to the next channel (450) andrepeats the process.

If the link master receives the ACK to its current HELLO_END (460), itknows that the link slave, for example, sensor 200, can hear it and thatit can hear the link slave. Based on that knowledge, the link masterdeclares the link state to be “up” (470). The link slave, however, doesnot yet know if the link master heard its ACK, so the link master sendsa second HELLO_END specifically addressed to the link slave to let theslave know that it heard its ACK packet (480). When the link slavereceives this second HELLO_END, it knows that the link master can hearit and it declares its link state to be “up”. The process of opening acommunication session between the link master and link slave iscompleted when the link slave ACKs the second HELLO_END packet (490).

FIG. 5 is a flow diagram describing the FHSS hunt protocol from theperspective of the link slave, for example, sensor 200. When the linkslave wishes to establish a digital communication link, the link slavehunts for the beacon HELLO packet that the link master is continuouslybroadcasting (510). It does this by listening for a carrier forapproximately one ms on every channel in sequence using the samepseudo-random sequence as the link master. If a carrier is detected on achannel (520), the slave continues to listen to the channel to try andreceive a HELLO_END packet (530). After the slave has received aHELLO_END packet, the slave checks to ensure that the packet is from alink master with which link slave wishes to establish a digitalcommunication link. If it is (540), the link slave transmits an ACKpacket type back to the link master containing information sufficient toidentify the link slave (570). Since the slave knows the link master'sidentity from the HELLO_END packet, the ACK is specifically addressed tothe link master that originated the HELLO_END packet. The slavesubsequently receives a second HELLO_END (580) and sends a second ACK(590) to complete the process. If the HELLO_END packet is not from alink master with which the link slave wishes to establish a digitalcommunication link (550), the link slave hops to the next channel (560)and repeats the process.

The link master and link slave use the same seven bit linear feedbackshift register to generate a pseudorandom hop sequence.

VI. Initialization

FIG. 6 is a flow diagram describing a sensor initialization protocol inthe system of FIG. 1. Sensor 200, which is a representative one ofsensors 30, 40, 50, is made operational by completing an initializationprotocol involving sensor 200, gateway 20 and installer 80. Upon powerup or reset, the firmware image on sensor 200 invokes radio module 230to establish a digital communication link with installer 80 using theinstaller Network ID and the FHSS hunt protocol (610). Installer 80 ispreferably GPS-enabled at this point. Once the link is established,installer 80 waits for the next valid position to be output from theGPS, and then writes the GPS coordinates and the operational Network IDof the logical communication group in which sensor 200 will participateto sensor 200 using a DMA write command (620). Installer 80 then closesits session with sensor 200, but remembers the Sensor ID transmitted bysensor 200.

Sensor 200 then opens a communication session with gateway 20 using thelearned operational Network ID and the previously described FHSS huntprotocol (630). Gateway 20 reads the GPS coordinates of sensor 200 usinga DMA read command (640) and writes the time of day to sensor 200 usinga DMA write command (650). Gateway 20 sends the GPS coordinates to Webserver 60 in association with the Sensor ID transmitted by sensor 200(660). Gateway 20 ends the communication session with sensor 200.

At that point, sensor 200 sets a “registered” flag in memory 214indicating it was able to talk to gateway 20. Sensor 200 thenestablishes another digital communication link with installer 80 usingthe Installer ID learned in the previous communication with installer 80and the previously described FHSS hunt protocol (670). Installer 80verifies that the “registered” flag is set and that the Sensor IDtransmitted by sensor 200 matches the remembered Sensor ID from theprevious session (680). Installer 80 then sounds a series of rapid beepsat the same pitch indicating successful initialization of sensor 200(690). In alternative embodiments, sensors may be equipped with theirown beepers or LEDs; however, it bears noting that such beepers or LEDsconsume extra power on such sensors.

VII. Reporting

FIG. 7 is a flow diagram describing sensor reporting within the systemof FIG. 1. In operation, sensor 200 reports periodic and, optionally,event driven structural integrity and operational information to gateway20. After initialization, sensor 200 enters sleep mode and the real timeclock on processing module 210 is reset (710). Sensor 200 wakes up whenthe timer expires (715) and monitors structural integrity information ifthe time for monitoring is indicated by the monitoring frequency onmemory 214. Sensor 200 then determines if an alarm threshold has beensurpassed. If so (720), sensor 200 establishes a link with gateway 20using the FHSS hunt protocol for reporting structural integrityinformation via interstitial interrogation (725). Interrogation isachieved through the issuance by gateway 20 of packetized DMA readcommands and the fulfillment by sensor 200 of those commands. After suchinterrogation, sensor 200 returns to sleep mode and the real time clockis reset. If no alarm threshold has been exceeded (730) but the linkestablishment frequency indicates time to report (735), sensor 200establishes a link with gateway 20 using the FHSS hunt protocol forreporting structural integrity information via periodic interrogation(740) prior to returning to sleep mode and resetting the real time clock(745). If the link establishment frequency does not indicate time toreport (750), sensor 200 returns to sleep mode and the real time clockis reset without interrogation. Of course, in some embodiments there areno alarm thresholds. In embodiments without alarm thresholds, the stepindicating to check whether an alarm is exceeded is bypassed.

Gateway 20 relays learned structural integrity information to Web server60 in periodic or event driven reports using a known address of Webserver 60, such as an IP address. In some embodiments, structuralintegrity information is transmitted to Web server 60 over an “alwayson” broadband Internet connection. In other embodiments, gateway 20relies on a dial up Internet connection. In dial up embodiments, gateway20 stores the structural integrity information in a local cache for atime before periodically dialing up the Internet service and uploadingthe information to Web server 60. However, gateway 20 also maintainslocal alarm thresholds that trigger immediate dial up of Web server 60if exceeded. Moreover, in dial up embodiments, gateway 20 preferablyreceives power from the phone line to render system 10 invulnerable toAC power outages within building 90.

VIII. Configuration Changes

Gateway 20 also utilizes digital communication links established forinterrogation to transmit configuration changes to sensor 200. Wheneversensor 200 establishes a digital communication link with gateway 20 forinterrogation of structural integrity information, gateway 20 may, inaddition to interrogating sensor 200 for structural integrityinformation using DMA read commands, issue DMA write commands to sensor200 that cause sensor 200 to store configuration changes in specifiedsegments of memory 214. In some embodiments, configuration changes arewritten during the first interrogation after receipt of theconfiguration information from Web server 60. In other embodiments,configuration changes are written during an interrogation that is at ornear a time specified by the human network administrator, and during thefirst interrogation after receipt of the configuration information if notime is specified. In either case, gateway 20 advantageously puts intodual use preexisting digital communication links between gateway 20 andsensors 30, 40, 50 that are established independently of configurationchanges.

The human network administrator preferably initiates configurationchanges to gateway 20 and sensor 200 from a standard Web browser onmonitoring station 70. The human network administrator preferably visitsa system management Web site hosted on Web server 60 and inputsinformation sufficient to identify the configuration changes to be made,the target device and, in some embodiments, the time the changes are tobecome effective. Web server 60 generates a command that describes thechange (i.e. sensor or gateway, firmware or other configuration change)and target device (i.e. gateway 20, sensor 200 or sensor group 30, 40,50). In response to a next contact by gateway 20 pursuant to an uploadof structural integrity information or a “server ping” initiated bygateway 20 after a period of inactivity, Web server 60 instructs gateway20 to implement the specified changes at the specified time, if any.

It will be appreciated by those of ordinary skill in the art that theinvention can be embodied in other specific forms without departing fromthe spirit or essential character hereof. As one of numerous examples,rather than continuous remote monitoring of gateway 20 over theInternet, “on demand” local monitoring may be conducted by plugging a PCinto the Ethernet interface on gateway 20 and retrieving structuralintegrity information cached by gateway 20. The present description istherefore considered in all respects to be illustrative and notrestrictive. The scope of the invention is indicated by the appendedclaims, and all changes that come within the meaning and range ofequivalents thereof are intended to be embraced therein.

1. An initialization method for a monitoring sensor, comprising:communicating to the sensor from an installer device first configurationinformation; communicating to a gateway from the sensor the firstconfiguration information; communicating to the installer device fromthe sensor first success information indicative of a successfulcommunication between the sensor and the gateway; and outputting by theinstaller device second success information indicative of a successfulinitialization of the sensor.
 2. The initialization method of claim 1,wherein the second success information is an audible sound.
 3. Theinitialization method of claim 1, wherein the first configurationinformation includes a network identifier associating the sensor with alogical group of devices.
 4. The initialization method of claim 1,wherein the first configuration information includes GPS coordinatesidentifying an approximate geographic location of the sensor.
 5. Theinitialization method of claim 1, wherein the gateway communicates to aWeb server the first configuration information.
 6. The initializationmethod of claim 1, wherein the transmitting and receiving steps areperformed over digital communication links.
 7. The initialization methodof claim 6, wherein the digital communication links are wireless links.8. The initialization method of claim 1, wherein the first successinformation includes an identifier of the sensor.
 9. An initializationmethod for a monitoring sensor, comprising: writing by an installerdevice to the sensor first configuration information; reading by agateway from the sensor the first configuration information; reading bythe installer device from the sensor first success informationindicative of a successful communication between the sensor and thegateway; and outputting by the installer device second successinformation indicative of a successful initialization of the sensor. 10.The initialization method of claim 9, wherein the second successinformation is an audible sound.
 11. The initialization method of claim9, wherein the first configuration information includes a networkidentifier associating the sensor with a logical group of devices. 12.The initialization method of claim 9, wherein the first configurationinformation includes GPS coordinates identifying an approximategeographic location of the sensor.
 13. The initialization method ofclaim 9, wherein the gateway communicates to a Web server the firstconfiguration information.
 14. The initialization method of claim 9,wherein the writing step is performed using a direct memory access (DMA)write command.
 15. The initialization method of claim 9, wherein thefirst and second reading steps are performed using DMA read commands.16. The initialization method of claim 9, wherein the first successinformation includes an identifier of the sensor.
 17. An installerdevice for facilitating initialization of a sensor, the installer devicehaving instructions executable by a processor for performing stepscomprising: transmitting first configuration information to the sensorfor further transmission to a gateway; receiving first successinformation from the sensor indicative of a successful communicationbetween the sensor and the gateway; and outputting second successinformation indicative of a successful initialization of the sensor. 18.The installer device of claim 17, wherein the second success informationis an audible sound.
 19. The installer device of claim 17, wherein thefirst configuration information includes a network identifierassociating the sensor with logical group of devices.
 20. The installerdevice of claim 17, wherein the first configuration information includesGPS coordinates identifying an approximate geographic location of thesensor.
 21. The installer device of claim 17, wherein the gatewaycommunicates to a Web server the first configuration information. 22.The installer device of claim 17, wherein the transmitting and receivingsteps are performed over digital communication links.
 23. The installerdevice of claim 22, wherein the digital communication links are wirelesslinks.
 24. The installer device of claim 17, wherein the first successinformation includes an identifier of the sensor.
 25. An installerdevice for facilitating initialization of a sensor, the installer devicehaving instructions executable by a processor for performing stepscomprising: transmitting a network identifier to a sensor; and receivingfirst success information from the sensor indicative of a successfulcommunication between the sensor and a gateway using the networkidentifier.
 26. The installer device of claim 25, further comprisingoutputting second success information indicative of a successfulinitialization of the sensor.
 27. The installer device of claim 26,wherein the successful initialization comprises joining a logicalcommunication group associated with the network identifier.
 28. Theinstaller device of claim 25, wherein the network identifier isassociated with a logical group of devices comprising one or moresensors and one or more gateways.
 29. The installer device of claim 25,further comprising associating GPS coordinates with the sensor.
 30. Theinstaller device of claim 25, wherein the installer device is a mobilehandheld device.
 31. The installer device of claim 25, wherein thetransmitting and receiving steps are performed over digitalcommunication links.
 32. The installer device of claim 31, wherein thedigital communication links are wireless links.
 33. A method forfacilitating initialization of a sensor, comprising the steps of:transmitting a network identifier to a sensor; and receiving firstsuccess information from the sensor indicative of a successfulcommunication between the sensor and a gateway using the networkidentifier.
 34. The method of claim 33, further comprising outputtingsecond success information indicative of a successful initialization ofthe sensor.
 35. The method of claim 34, wherein the successfulinitialization comprises joining a logical communication groupassociated with the network identifier.
 36. The method of claim 33,further comprising associating GPS coordinates with the sensor.
 37. Themethod of claim 33, wherein the transmitting and receiving steps areperformed over digital communication links.
 38. The method of claim 37,wherein the digital communication links are wireless links.
 39. Themethod of claim 33, wherein the sensor is adapted to monitor structuralintegrity of a building.